利用多种类型资料,对2009年6月29—30日引发鄂皖境内梅雨锋特大暴雨过程的天气形势和中尺度对流系统(MCSs)进行了初步分析,揭示了梅雨锋暴雨系统的多尺度结构特征,并用中尺度模式WRF对梅雨锋暴雨系统进行了9km三重双向嵌套大区域精细模拟,再采用Morlet小波变换对模式输出进行空间带通滤波,分离出α、β和γ中尺度系统,对不同中尺度系统的热力动力三维空间结构特征进行了研究。结果表明:梅雨锋特大暴雨由梅雨锋上多个不同尺度的MCSs活动造成,这些不同尺度的MCSs在卫星云图和雷达回波上呈现出不同的特点。在α、β和γ中尺度上,梅雨锋暴雨中尺度系统在水平和垂直方向上的动力、热力结构特征存在着明显的差异,α、β中尺度系统具有明显的垂直环流,而γ中尺度系统则具有惯性重力波特征,往往嵌套在α、β中尺度系统内发生发展。最后,提出了典型梅雨锋暴雨系统的物理概念模型。
Based on the multiple-type observational data,this paper preliminarily analyses the meso-scale convective systems(MCSs)and weather background producing an extremely heavy rain along the Mei-yu front in Hubei and Anhui provinces during 29—30 June 2009,and investigates the multi-scale structure features of the Mei-yu frontal rainstorm system.Then the meso-scale numerical model WRF with large domain and 9 km horizontal resolution is used to carry out a 3-domain-nested fine simulation for the heavy rain process.Morlet wavelet transformation is carried out to do spatial band-passing filter for the model outputs,and the meso-α,-β and-γ-scale systems are separated out,in such a way that the three dimensional spatial dynamic and thermodynamic characteristics of the meso-scale systems with different scales are studied.The results are as follows.The extremely Mei-yu frontal heavy rain is directly resulted from several MCSs with different scales,which are of different features on satellite cloud images and radar echoes.On meso-α,-β and-γ-scales,the Mei-yu frontal heavy rain system has obvious different dynamic and thermodynamic structure features in horizontal and vertical directions.The meso-α and-β-scale systems have obvious vertical circulation,while meso-γ-scale system has some features of inertial gravity waves and usually develops in meso-α and-β-scale system.Lastly,a physic conceptual model is advanced for the typical Mei-yu frontal rainstorm system.